The Patient Centered Medical Home (PCMH) and the Chronic Care Model (CCM) are complementary clinical intervention frameworks that are commonly invoked to support better type 2 diabetes (T2DM) outcomes in primary care. Self-management Support (SMS) is a core component of both the PCMH and CCM, and focuses on the central role of patients in managing their illness by engaging with and adopting healthy behaviors that promote optimal clinical outcomes. Despite its recognized importance, SMS programs for diabetes continue to demonstrate limited effectiveness in the real-world of primary care. SMS is comprised of two complementary and interactive components: (1) patient engagement (e.g., the process of eliciting and responding to patients emotions and motivations related to health behaviors), and (2) behavioral change tools (e.g., selecting specific goals, creating action plans). While several sophisticated SMS programs have been developed for T2DM, the vast majority are designed with a narrow focus on behavioral change tools, largely ignoring unique aspects of the patient context that drive and maintain health behavior. Considerable clinical research suggests that the addition of a structured, evidenced-based program of patient engagement can maximize the effectiveness of SMS programs for patients with T2DM in primary care. To date, however, there has been no systematic study of the degree to which fully integrating enhanced patient engagement as part of SMS will increase the initiation and maintenance of behavior change over time, and for which kinds of patients enhanced patient engagement is essential. To address this gap, we propose to compare a state-of-the-art, evidence-based SMS behavior change tool program, called Connection to Health (CTH), with an enhanced CTH program that includes a practical, time-efficient patient engagement protocol, to create a program with an integrated and comprehensive approach to SMS, which we call Enhanced Engagement CTH (EE-CTH). The current study will directly test the added benefit of EE-CTH to CTH with regard to self-management behaviors and glycemic control in resource-limited community health centers, where vast numbers of patients with T2DM from ethnically diverse and medically vulnerable populations receive their care. We will use an effectiveness-implementation hybrid design, employing the RE-AIM framework to test these two SMS programs for T2DM. This will provide critical information that will support dissemination and implementation of effective SMS programs in resource-limited primary care settings, serving diverse and medically vulnerable populations with much to gain from improved SMS.